To send a text at a later time in Google Messages, start a new conversation or open an existing one, type your message, then tap and hold the Send button. Select "Pick date and time," choose your desired time, and hit Save to schedule the message.
If you're using Samsung messages, type in your text and hit the + sign next to the text box, a menu will show up where you can select schedule message. You can select the date and time you wish to send the message.
